Several methods are available to detect a moving object from the image inputted by a TV camera. The moving object is, for example, a car or a plane which is moving in a background. When the moving object and the background are taken by the TV camera, the method to detect the moving object from the image is as follows.
(1) "Motion Tracking with an Active Camera" D. Murray, A. Basu (PAMI, Vol. 16, No 5, 449-459, 1994). In this method, the movement amount of the camera is previously known. The correspondence of the moving object in image sequences is calculated. In short, by using the movement amount of the camera, the movement of the object is predicted in the images. PA1 (2) A plurality of characteristic points are set in plural images. The apparatus searches in the plural images for an area whose peak points correspond to the characteristic points. In this way, Affine transformation parameters between the plural images are calculated. By using the Affine transformation parameters, the background is shifted between the plural images to detect the moving object. PA1 (3) In Japanese Patent Disclosure (Kokai) PH7-110864, a two dimensional Laplacian filter is multiplied with a moving vector field in the image. By using the output value, a group of background vectors is separated from a group of moving object vectors in the image to detect the moving object.
In the above-mentioned methods, the uncertainty of the movement amount in the image is not taken into consideration; nor is the reliability of the determination of the moving vector by scene including the background.
When the object moving in the background is taken by the camera, it is necessary that the area of the image be divided into a background and a moving object. In this case, the background is separated from the moving object according to the moving vector of each area in the image. However, as mentioned-above, the moving vector of the image calculated by the prior method is uncertain. Therefore, if this kind of moving vector is used uniformly, it often happens that the background is not correctly separated from the moving object. Even if the uncertainty of the moving vector is taken into consideration according to situation of the scene as a whole, it is difficult to correctly detect the moving object reflected in the situation of the scene. This problem occurs in cases where moving, rather than stationary, cameras are used.